The present invention relates to a driven axle for vehicles having independently guided wheels. The wheel is guided by a wheel bearer and the axle has a wheel shaft mounted in the wheel bearer. A first double universal joint adjoins the wheel shaft, and has a movable and fixed side, the movable side being on the wheel bearer side. The movable side has an axial displacement path in the transverse direction of the vehicle which depends on the flexure angle of the double univeral joint. The axle also has axially displaceable drive shafts articulated between the first double universal joint and the second double universal joint.
Axles of this type are known as steerable rigid axles and are described in Fahrzeugtechnik (Vehicle Technology) 4th edition, page 280, author: Reimpell. These axles have the characteristic that, during the flexure of the double-jointed universal shafts caused by steering movements of the wheels, the drive shaft is displaced inwards in the transverse direction of the vehicle depending on the amount of steering turn or the size of the overall flexure angle. Because of this displacement movement of the drive shaft, such double-jointed universal shafts are subject to wear. This is a reason why universal joint shafts having a synchronously running fixed joint, so as to be free from displacement movements, have been installed in driven axles having independently guided wheels. The axle shafts of these wheels have to be able to follow spring deflection movements of the wheels in an essentially vertical plane. However, universal shafts equipped with synchronously running fixed joints are not suitable for commercial vehicles because of the torques transmitted in such vehicles.
The object of the invention is to provide a driven axle of the above-described type in which the drive shafts, articulated on the wheel bearer by a double universal joint, are able to compensate for spring deflection movements of the wheels to keep the longitudinal displacements of the movable side of the double universal joints negligibly small. Moreover, it is intended for the axle to be used advantageously in particular in heavy commercial vehicles.
This object is achieved in a driven axle according to the invention by providing that the distance between a center of rotation of the wheel bearer and a first double universal joint is greater than the distance between the first double universal joint and a second double universal joint. By this provision, the axial displacement of the first double universal joint is substantially reduced during flexure of the first double universal joint.
In the axle design according to the invention, during spring movements, the articulation point of the double universal joint of each double-jointed universal shaft, together with the wheel bearer, follows along a track curve determined by the wheel guide members. The local radius of curvature of this track curve is greater than the distance between the wheel bearer side and body-side articulations of the drive shafts.
During spring movements, the axial displaceability of the drive shafts enables an axial movement to be superimposed on the drive shafts during their pivoting movement about the articulation point on the body side, to axially displace the drive shafts in the opposite direction to which they are normally displaced during flexure of the double-jointed universal shafts. Moreover, preferred embodiments provide that the drive shaft parts which are displaceable relative to one another essentially remain stationary, as viewed in the axial direction, during each flexing phase of the double-jointed universal shafts.
By locating the steering axle on the movable side of the double universal joint in a further advantageous embodiment of the invention, the independently guided wheel of the axle is pivotable about a steering axle without allowing disadvantageous axial displacement within the drive shaft of the double-jointed universal shaft resulting from steering movements.
Further objects, features and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings, which show for purposes of illustration only, embodiments constructed in accordance with the present invention.